1. Field of the Invention
This invention relates to a grinding machine for grinding the outer surface of a rod-like object. More particularly, this invention relates to a grinding machine which includes roughing and finishing tools which can rough and finish the outer surface of a rod-like object in a continuous manner without replacing the tools.
2. Description of the Prior Art
In order to grind the outer surface of a rod-like object, at least two grinding steps are required for roughing and finishing. Shaving with tools for use with lathes and grinding with whetstones or buffing cloths are generally adopted in the grinding process.
Incidentally, in shaving with tools for use with lathes, the feed of a carriage has to be slowed down. In addition, it is sometimes necessary to stop operation when exchanging tools. Therefore, the grinding operation suffers from a low working efficiency. Moreover, the accuracy of machining is so poor that the process is unsuitable for finishing such articles as gravure rolls for which a high finishing accuracy is particularly required.
Grinding with whetstones is superior in finishing accuracy. That is, it has an advantage over other finishing processes in that a beautiful surface with twill can be obtained. But on the other hand, a lot of time is required to exchange whetstones, which necessitates stopping the operation and thus lowers the working efficiency. Additionally, the employment of whetstones requires the application of an anticorrosive treatment on them and apparatuses are needed for feeding a solution in order to prevent the choking of the textures of the whetstones and for filtering and recycling the spent solution exhausted therefrom. Accordingly, the cost of the equipment inevitably increases and the disposal of the waste solution is also very expensive.
Grinding with buffing cloths is inferior in durability since the grinding effect wears off soon. In addition, it is difficult to produce a well finished surface because cloths with choked textures tend to cause scratches. As such, a good finish cannot be obtained by buffing.